A kinescope is typically provided with 4 mounting lugs at the respective corners. During assembly, the kinescope is mated with the television (TV) cabinet and screws are driven through the holes in the mounting lugs to fixedly secure the kinescope to the cabinet.
After assembly of the kinescope to the cabinet, the electron gun assembly of the kinescope is activated to see if there is any misalignment between the raster produced on the TV screen and the cabinet opening. The screen misalignment is manifested as black edges between the lighted raster and the bezel or rim defining the cabinet opening. If there is any misalignment, the screws holding the kinescope are loosened, the position of the kinescope is readjusted, and the screws are then retightened. The holes in the mounting lugs are purposely made larger than the kinescope mounting screws, so that the position of the kinescope can be readjusted after loosening the screws. This technique is time-consuming and costly.
The problem of correct positioning of the kinescope screen is further compounded by the minimal overlap (e.g., 0.015 inches) between the screen (i.e., phosphor area) and the bezel surrounding the cabinet opening. Other factors--such as manufacturing variations involved in the positioning of the kinescope mounting lugs, etc., also contribute to the difficulty of correctly positioning the kinescope screen relative to the cabinet opening.